A 1.5D transducer for medical ultrasound

The current shift to digital beamforming technology holds promise for regular and rapid increases in the number of channels in a medical imager. A 1D transducer typically utilizes 125 elements, while a fully sampled two-dimensional aperture requires of order 10000 elements. Currently, channels are still expensive, so it is of interest to evaluate how much performance can be improved with a moderate increment in channel count. How may we maximize the impact on voxel size? The number of elevational elements is constrained by how complex the interconnections can become. It is impractical to significantly degrade the azimuthal resolution from the 1D case. We present beam profiles and images from a first attempt at judicious use of a 256 channel imager. Simulations and experiments allow us to explore compromises among a number of design goals. We have fabricated a transducer with several elevational rows which reduces the slice thickness of the image while maintaining full azimuthal resolution